PRÉ-MELHORAMENTO DE MILHO PARA RESISTÊNCIA À MANCHA-BRANCA E À FERRUGEM-POLISSORA
DOI:
https://doi.org/10.18512/1980-6477/rbms.v16n2p273-286Keywords:
Zea mays, FitopatologiaAbstract
RESUMO - O Banco Ativo de Germoplasma de Milho (BAGMilho) preservado na Embrapa Milho e Sorgo mantém cerca de 4.000 variedades. Entretanto, essas variedades não têm o padrão agronômico das cultivares comerciais, o que reduz o seu potencial do uso direto. O pré-melhoramento possibilita o desenvolvimento de genótipos com maior poten-cial de uso por meio da hibridização entre acessos do BAGMilho e genótipos melhorados. O objetivo deste trabalho foi avaliar famílias endogâmicas obtidas de cruzamentos entre linhagens-elite e os acessos do BAGMilho composto-fonte de resistência à mancha-branca e composto-fonte de resistência à ferrugem-polissora quanto à reação a patógenos, produtividade e caracteres agronômicos. Famílias endogâmicas derivadas de retrocruzamentos entre estes compostos-fonte de resistência e linhagens-elite foram avaliadas em cruzamentos com testadores dos grupos heteróticos duro e dentado. Os ensaios foram conduzidos em Sete Lagoas e Nova Porteirinha em duas épocas de semeadura. Os resulta-dos permitiram selecionar as famílias endogâmicas MB130, MB181, MB164, FP109, FP133, FP104, FP120, FP112, FP103 e FP140 para uso em cruzamentos com linhagens do grupo heterótico duro e as famílias endogâmicas MB024, MB032, MB083, FP028, FP036 e FP020 para uso em cruzamentos com linhagens do grupo heterótico dentado.
Palavras-chave: recursos genéticos, fitopatologia, Zea mays, Pantoea ananatis, Puccinia polysora.
MAIZE PRE-BREDING FOR RESISTANCE TO WHITE SPOT AND POLYSORA RUST
ABSTRACT - The Maize Active Germplasm Bank (GBMaize) preserves about 4,000 varieties of maize. However, these varieties do not have the standard commercial performance that reduces their potential of agricultural use. Pre -breeding enables the development of greater agricultural use of genotypes by hybridization between the accessions from GBMaize and improved genotypes. The aim of this study was to evaluate inbred families obtained from crosses between inbred lines and accessions of GBMaize called source of resistance to white spot composite and source of resistance to polysora rust composite in crosses for resistance to pathogens, grain yield and agronomic traits. Inbred families derived from crosses between inbred lines and source of resistance to white spot and source of resistance to polysora rust composites were evaluated in crosses with flint and dent heterotic patterns testers. The trials were conduc-ted in Sete Lagoas and Nova Porteirinha in two sowing dates for the evaluation of resistance to pathogens, yield and traits of agronomic importance. The results allowed select inbred families MB130, MB181, MB164, FP109, FP133, FP104, FP120, FP112, FP103 and FP140 for use in crosses with flint heterotic pattern and inbred families MB024, MB032, MB083, FP028, FP036 and FP020 for use in crosses with dent heterotic pattern.
Keywords: renetic resources, phytopathology, Zea mays, Pantoea ananatis, Puccinia polysora.
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